Conventional gene dosage and expression analysis strategies such as semi-quantitative Southern and northern blot analysis have been supplanted by more efficient polymerase chain reaction (PCR) based sequence polymorphism detection. Use of standard PCR protocols, coupled with reverse transcriptase for RNA analysis, has advanced the speed, throughput, and ease with which semi-quantitative endpoint data analysis can be achieved. However, endpoint analysis of PCR products is of limited use for quantitative determinations because it does not represent the linear phase of the process. The usefulness of endpoint PCR analysis is further complicated by the introduction of post PCR variations, including sample handling and visual data collection errors. All of these considerations make it technically difficult to derive accurate quantitative data from endpoint PCR analysis. Instruments such as the Applied Biosystems (ABI) PRISM 7700 Sequence Detection System have increased the efficiency, speed and scope of sequence detection for quantitation of genes and gene transcripts. Comparative and direct quantitative analyses are possible due to the PRISM 7700's reproducible real time fluorescence data collection. This instrument would facilitate common applications including genotyping and transgene copy number/gene dosage detection. More difficult procedures, including pathogen load determination and quantitative gene expression analysis, could be carried out more rapidly and cost effectively. The Jackson Laboratory (TJL) is well recognized for its scientific contributions in mammalian genetics. Approximately 40% of research projects at TJL utilize semi-quantitative DNA and RNA analysis techniques. Based on the cost savings alone, throughput of these current projects would be increased 34% with the availability of this system. Projects of one third (11) of our staff members, funded by 16 NIH grants would be greatly enhanced by access to this instrumentation. The scope of future projects would also be broadened, significantly improving the overall productivity of this institution's scientific staff. The scientific community would be served by enabling TJL staff to screen, characterize and make available new models for human diseases available more rapidly. Funds are requested to purchase the ABI PRISM 7700 Sequence Detection System, necessary computer hardware, operating/data analysis software and uninterruptible power supply.